Her ulti is a bit strong, but well - it has about 130s cd on 1st rank, plus it dosen't deal that much dmg to single target - and yi has such thing once per 5s? 10s? oh - and it has melee range.
you have to cc her in right moment - her E gives her a GIANT boost to dps(108% atk speed at rank 5!) - she is shining while doing this.
Riposte is nice harassing tool but it only reflects: basic attacks, creeps attacks, big mosnter attacks. so while fighting near creeps her E is way waker.
Her Q is nice chasing tool - but to be honest - it is weaker version of renekton's one - she has to target someone to use it, but she has slightly bigger range.